Mopar Performance Distributor adjustable advance?

You guys make me want to cry. Why? Because people assume that everyone understands what they are talking about. I am not an electrical engineer, or distributor guru, or carburetor airbleed tip in guru either. I have FBO parts in 2 cars, one is running fine with them. The other one isn't together yet, but has the FBO distributor and module. All came recommended from a respected engine builder that occasionally makes comments on this site. Sometimes I feel like I am back in the Army, and my poncho fell apart on a forced march and now I am on the side doing push-ups for embarrassment, so that it doesn't happen again! I have no idea what those red gauges do yet, I have a set, they came with the new distributor. Just haven't gotten that far. Maybe Red Green can help me with some duct tape! I will keep watching, we're all in this together.
Just ask whatever you ain't gettin and we'll do our bestest to help you understand. The red keys for example. Each one is a different thickness. You loosen the advance screw on the breaker plate on those distributors and use the keys to stick in the slot to give you "whatever" advance you're looking for. The length of that slot controls how much advance you get. Bigger slot = more advance.